This gun was very hard to glimpse in the original theatrical cut of ALIEN. Mostly it was just visible in the holsters on the space suits.

Yep, but it was displayed on the cover of STARLOG #26 and in THE BOOK OF ALIEN (in France it was released as a special edition of METAL HURLANT, with a different cover... and all texts translated into french, of course), that's where if first saw it... and immediately fell in love with it !

Here is my NOSTROMO GUN, a second generation Shawn Morgan kit built by him. I've replaced the bottom scope with a screen accurate Star Wars / rebel blaster scope from Master Replicas. I still have work on this one to make it look closer to the screen-used gun(s) but I think it's a good start !

BTW, Steve and Richie (ALIEN EVA SUIT project) told me a 3rd generation Nostromo gun was currently on Shawn's bench... Can't wait to see it !!!

Looks like on the prop they closed the bolt opening and ejection port and removed the bolt handle.From the script they were supposed to be rail guns so they were not necessary.Cameron's weapons are kind of low tech next to railguns but I guess he didn't think anyone would know any better.